The purpose of this contract is to provide 1) a closed, conventional facility for the breeding and maintenance of pedigreed inbred and cogenic mice which are used for plasmacytoma experiments; 2) laboratory facilities for the construction of BALB/Can cogenic strains of mice that carry segments of DBA/2 chromosomes, including the testing of mice using recombinant DNA technology for detecting appropriate marker genes; 3) necessary procedures for inducing plasmacytomas (such as by intraperitoneal injection of pristane, by injection of transforming retroviruses, and the administration of various agents in the drinking water of diet that inhibits plasmacytomagenesis (e.g. indomethacin); 4) a facility for maintaining and observing mice and detecting placytomas in mice during the time when tumors develop; 5) a facility for transplanting, preserving by cryopreservation, and recovering of tumors for purposes of shipping the tumors to other laboratories; 6) a facility for storing frozen tumor tissues and other genomic experiments; and 7) a facility for the maintenance of wild mice.